Brake operating device



0. J. BRATZ BRAKE OPERATING DEVICE March 16, 1954 2 Sheets-Sheet 1 Filed March 5, 1950 INVENTOR OTTO J.BRATZ ATTORNEY March 16, 1954 o. J. BRATZ BRAKE OPERATING DEVICE 2 Sheets-Sheet 2 Filed March 5 INVENTOR OTTO J. BR AT ATTORNEY Patented Mar. 16, 1954 UNITED STATES PATENT OFFICE BRAKE 01 112 2226 DEVICE I can Ghain 8t Cable Company, Inc Bridgeport; 001111., a corporation of New York Application March 3, 1950, Serial No. 147,531

This invention relates to s'o-called po wei: multi pliers and has particular reference tosuch mechanisms in conjunction with automotive vehicular brakes.

* "lihehand operated brakes of automotive vehicles have been operated by means of Bowden' wires for the transmissionof the force and mo tion between the driving compartment and the linkage below the floor of the vehicle. The total leverage between the drivers hand on the brake handle and the cables or rods connected. to the whee} brakes is required to be about eight to one; Because ofspace limitations, it is diflicult, if not impossible, to have all this leverage below the floor, when utilizing conventional linkages and, therefore, the leverage below the floor is limited to about three to one. The remaining mechanical advantage is realized by the instaliation of a linkage in the driving compertinent, between the actuating handle of the brake and the transmission cable'of the Bowden wire.

Use of any leverage between the handle or the brake and the Bowden wire of necessity requires that the Bowden wire transmit greater forces than would' otherwise be the case. Bowden Wires,

when curved, display greatly increased frictionand decreased efiiciency as'the' force transmitted increases. I

It" is an object of the present invention to pro vide' a power multiplier for a vehicle brake" with sufficient mechanical advantage to permit opera-*- tion by direct application of the force onthe' brake handle, said multiplier belng'p'articul'arl y' adapted to operate with cable or strand."

Referring now tothe drawings which in. con with the description thereof shovvpre ferred embodiments of the invention:

Fig; 1 is a perspective view of one-form of the device: with thehousing cover removed to exposethe interior;

Fig. 2 isa diagrammatic showingof the prin Fig; 5 is an elevation-of part of the mechanismofa-still-further modification of the form of theinvention shown in Fig. 1.

Referring first to the'form'of device" shown in Figs; I to 3 the device includes a: housing It; forming a covering to protect'theparts from dirt and moisture, and serving to hold' thepart's'in 1 Claim. (Cl. N -110) 2 assembled relation, A lid or cuter H closes the open side of: this housing.

Powerinput to the device is through the cable [2, which has a suitable fitting at the end there of, such as, for example, is indicated by the numerai l 8', for attachment to the Bowden wire or lever extending to the driving compartment of thevehicie. For the reasons stated above, the Bowden wire intended to be without leverage devices in the driving compartment to keep the tension on the Bowden wire at a minimum.

"The cable I2 is shown" as extending through a fitting M", which is in the form of a shouldered bushing, with a cap 55 secured to its outer end,

, the cap being of yieldabiematerialto lightly grip the cableand serve to prevent entry of dirt or water through the fitting #4. 0n the inner end the fitting i=4 isp'rovide'd with a groove which receives a notchiG in aspring plate Ill The plate thus hoids the fitting piece;

The cable passes} around a sheave Ia and the lower portion [2a is secured to the casing 10 by means of a-fltting' l9 swaged on the end of the cable.- This fitting is threaded on its outere'ncl for the reception oi as nut 21;,- to' hold it" in place; In use, the threaded portion of the fitting is securedto a frame element of the 'vehicle; as the} pertinent the cable [2a to which it is attachedse'rves asthe reaction cable ofthe inecl iaiiisirii The spring element l i has a notch 21, which-fits: over a squared portion 22 of the fitting and prevents'th'e fitting from turning. At the sametime; the fitting retains the spring memberin place, aided by a retaining strip 23- secured to the casing lo by spot welding or any other means desired;

sheave l8 has been shown as fabricated of sheet metal by spinning or stamping, in twohalves; which may be spot welded or otherwise secured together. As can be-seen, each half-has an offset flange 24 on the web 25, forming the gether'a tread upon-Which the cable lies. incidentally; the'fl-anges- 2 4 are of such d-ian'ueter as to neariyfill the-casing I'D so'that-thereisinsuflicient-s'paee for the cable #2" to leave thegineve btwn the flanges i 'vitl l-bl lt taking the sheavesout-of' the casing.

The webs- Ziahd thefianges- 2'4 ofthe' sheavehalves are slotted at one point, to admit a bail fitting 2'6 swaged' 0'1 otherwise secured to the cable: The slotand ball-cooperate to'preve'nt' any slippagebetweenthe cable about the tread of the sheave I8. It is who understood that the ball"! G- on thecontinuous cable couldre'adi'ly be replaced by two balls, on' the ends of two sepa rate cabi'es corresponding to the parts fraud tic A further tread 21 is formed on each sheave half by the conical portion 28 and fiange 29, for the reception of the power output cables. As shown the power output cable treads are smaller in diameter than the tread upon which the cable l2 lies.

For the purpose of symmetry, to prevent introduction of forces tending to cock the sheave around, the power output is taken from both sides of the sheave on the treads 21 mentioned. To equalize the tension on each cable part of the power output, the cable is shown as continuous, passing from one side of the sheave to the other through the slot in the web and is slidable therein. A struck-out portion 30 on each of the webs 25 forms a rounded surface around which a cable 3| can pass without injury. This cable has its ends secured to a wide fitting 32, at points spaced to maintain the parts parallel. A cylindrical portion 33 of the fitting passes through a bushing 34 secured to the wall of the casing, this bushing being provided on its exterior end with a soft rubber cap 35 to serve to prevent entry of dirt or moisture. The cylindrical portion 33 of the fitting is threaded for the reception of nut 36, which holds a spring retainer washer 31 against movement to the right. A spring 38 surrounding the bushing and fitting, is held under compression between the exterior of the wall of the casing l0 and the washer 31 and urges the parts in brake releasing direction, thus assuring that all cables are under tension at all times. A brake cable equalizer yoke 39 is secured to the fitting 32 by means of nuts 40. For the purpose of preventing rotation of the fitting 32, a

channel member M is provided on the interiorof the casing l0, permitting free longitudinal movement of the fitting but limiting its rotational movement.

It will be noted that the casing is tapered at one end as shown at Ma. The corner 42 so formed is arranged so that when the brakes are released the sheave rests therein and is thus held against rattling. To further diminish rattling, a spring member 43 is inserted in the bore of the sheave, and has a portion 44 projecting beyond the plane of the side of the sheave to engage the cover H and prevent axial move- \ment of the sheave.

The three cables, it will be noted, are disposed with cables l2 and 3! wound counterclockwise, on their treads, while cable I2a is wound on; its tread in a clockwise direction, as the device.

is shown in Fig. 1. This arrangement is shown in Fig. 2. (The understanding is, of course, that the direction of'winding does not matter, except that [2 and 3! must be the same, and lza opthe fitting l9 and the nut 26, the sheave rolls along the cable [20. when tractive motion is given to the upper part of the cable I2. Thevelocity of their diameters. size of the mechanism is not dictated by the vices shown in Figs. 1 to l.

4 the top of the sheave imparted by the pull on the input cable is represented by arrow B and, as the sheave rotates in a counterclockwise direction about A as an instantaneous center when rolling along the cable IZa, the velocity imparted to the cable 3! is represented by the arrow C. As, neglecting friction, the forces are inversely proportional to the velocities in mechanisms of this type, it can be seen that the force multiplication in the described mechanism is directly de endent upon the difference in diameter of the two treads, rather than upon the ratio of For this reason, the physical multiplication desired, but only by the travel of the output cable needed and such considerations as the minimum safe radius for the cable sheaves.

In Fig. 4 there is shown a modification of the device illustrated in Figs. 1 to 3. structurally, the device of Fig. i is practically identical with the device of Fig. 1 but is modified to permit the power output cable to extend from the same end of the housing as the power input cable. In this form, the cable 5| passing around the sheave 52 has One end secured to a fitting 53 to be connected to the Bowden wire, and the other end connected to a fittin 54 carrying spring 55 and yoke 56, this end being intended to be the power output or the device. A continuous cable 51, having each end secured to a wide fittin 58, and passing around the smaller radius treads 59 of the sheave 52, serves as the reaction member of the device, the fitting 58 being secured to the housin it by means of a pair of nuts, one of which, indicated by the numeral 6!, is visible in the figure.

In operation, tractive motion of the fitting 53 causes the sheave 52 to rotate about the points of tangency of the cable 5'! on the small treads which results in a reduced motion of the power output ortion of the cable 5| to the right in Fig. 4. v

In Fig. 5 there is shown a fragmentary portion of a still further modification of the de- It is often desirable to provide a varying multiplication ratio in a brake system. For instance, the effort needed to bring the brake shoes into contact with the drum is comparatively low, and the multiplication ratio during that part of the operation can be lower than the ratio during application of braking pressure. In Fig. 5 the sheave 65 has the larger tread 66 eccentric with respect to the smaller tread 61. Accordingly, as the tractive movement of the fitting 68 proceeds, the force multiplication of the device increases as the distance between the points of tangency of the lower cables 69 and it decreases. Although this variation of force multiplication is attained in the present device by utilizing eccentric circular treads, it is of course to be understood that the same efiect can be attained with non-circular treads as well.

It is to be further understood that the above described structures are intended to be only 11- lustrative of theinvention, and that considerable modification of the shown structure is possible without departing from the spirit of the invention as expressed in the following claim. The expression cable used in the description and claim is intended to convey the idea of a flexible element capable of transmitting a force by tension, and to include wire or even fiat bands,

as well as various stranded structures.

I claim:

A brake operating mechanism comprising a sheave having a circular tread and a circular flange on each side of said tread, a housing having parallel walk closely engaging the peripheries of the flanges, thus constraining said sheave to rotational movement about its axis and rectilinear movement at right angles to said axis, a tapered portion at one end of said housing for engaging said flanges at one end of the path of rectilinear motion of said sheave, said sheave havmg further a pair of circular treads concentric to the first-mentioned circular tread of mutually equal radii less than the radius of the first mentioned tread, one of said pair of treads lying on each side of the larger radius tread, a cable passing in a return bend around the larger radius tread and anchored thereto, one end thereof being anchored to the housing, the portion of said cable between an anchorage thus being a reaction cable, the other end of the cable being free to constitute the remaining portion of the cable a power input cable, a pair of power output cables comprising parallel cable wound on the smaller radius treads in the same clock direction as the power input cable is wound, and leaving their treads at points adjacent the points departure of the reaction cable from its tread.

OTTO J. BRATZ.

References Cited in the flle of this patent UNITED STATES PATENTS Number Name Date 1,071,466 Royle Aug. 26, 1913 2,027,275 Foster Jan. 7, 1936 2,080,131 Harper May 11, 1937 2,081,737 Chittick May 25, 1937 

